The present invention relates to cameras having removable image bearing media.
Current silver halide film cameras have displays for indicating settings and status conditions, such as frame number, of the camera. Often, the display uses twisted nematic liquid crystals that that requires continuous electrical drive to display information. Cameras with this type of display can be turned on only for short periods of time to preserve battery life. When the cameras are turned off, the liquid crystal display goes blank. An operator must turn on the camera to determine the status of the camera. These cameras typically incorporate a high voltage supply to drive an electronic flash built into the camera, and utilize cartridges that contain the film in a light tight environment.
Many digital cameras use liquid crystal displays to display a captured image. Displays in these cameras are also nematic liquid crystals displays that can drain an electronic camera high voltage supply in a short period of time.
Many digital cameras also use removable memory cards to store images. There is no way to tell how much capacity remains or what images reside on these memory cards.
Accordingly, it is an object of the present invention to provide a display on image bearing medium.
It is another object of the present invention to provide a display on image bearing medium that presents an image to a viewer even when the voltage to the display is removed.
These objects are achieved in a camera having a removable image bearing medium and an electronic flash charging unit for providing a source of high voltage, comprising:
(a) a display on the removable image bearing medium;
(b) means for selectively coupling such high voltage to the display, the display including material which is effective in a first condition in response to a selectively applied high voltage for changing the condition of the material to display an image and effective in a second condition for preventing the display of the image, the material being selected so that after displaying the image such material continues to display the image after the removal of the applied high voltage; and
(c) voltage applying means for causing the coupling means to selectively apply the high voltage in the charging unit to the display for causing the material to be effective in the first condition to produce the image and for removing the applied high voltage so that the material continues to display the image, the voltage applying means selectively applying a voltage less than the high voltage for causing the material to be effective in the second condition.
An advantage of the present invention is that it permits the use of displays which require a high voltage source to display images.
A feature of the present invention is that the high voltage supply in the electronic flash unit can be used as a source of high voltage for the display on the image bearing medium.
It is a feature of the present invention it permits display of images on the image bearing medium when high voltage to the display is turned off.
It is a further feature of the present invention to provide an indication on the image bearing medium of the storage capacity remaining.